By checking the chemistry underlying the concept of "supramolecular cluster catalysis" we identified two major errors in our publications related to this topic, which are essentially due to contamination problems. (1) The conversion of the "closed" cluster cation [H3Ru3(C6H6K6Me6)(2)(O)](-) (1) into the "open" cluster cation [H2Ru3(C6H6)(C6Me6)(2)(O)(OH)](-) (2), which we had ascribed to a reaction with water in the presence of ethylbenzene is simply an oxidation reaction which occurs in the presence of air. (2) The higher catalytic activity observed with ethylbenzene. which we had erroneously attributed to the "open" cluster cation [H2Ru3(C6H6)(C6Me6)(2)(O)(OH)](-) (2),was due to the formation of RuO2 (.) nH(2)O, caused by a hydroperoxide contamination present in ethylbenzene. (C) 2004 Elsevier B.V. All rights reserved.